Methods and systems of transferring, docking and processing substrates

[0001] This application is a continuation-in-part of U.S. patent application Ser. No. 12/319,231 entitled “Methods and Systems of Transferring, Docking and Processing Substrates” and filed Dec. 31, 2008 now U.S. Pat. No. 7,897,525, which is incorporated by reference herein in its entirety.

[0002] This application is related to U.S. patent application Ser. No. 12/319,225 entitled “Systems and Methods for Substrate Processing” and filed Jan. 3, 2009; U.S. patent application Ser. No. 12/319,224 entitled “Integrated Facility and Process Chamber for Substrate Processing” and filed Jan. 3, 2009; and U.S. patent application Ser. No. 12/319,223 entitled “Methods and Systems of Transferring a Substrate to Minimize Heat Loss” and filed Jan. 3, 2009, all of which are incorporated by reference herein in their entirety.

[0003] The disclosed embodiments relate generally to systems and methods for processing of substrates, such as but not limited to glass and other substrates used in the solar or photovoltaic industry, and wafers used in the semiconductor industry. More particularly, some embodiments relate to systems and methods for substrate processing comprising one or more mobile transverse chambers for transporting substrates between process modules.

[0004] Fabrication of semiconductors, flat panel displays, and photovoltaics (PV) or solar cells require multiple processes, such as etching, chemical vapor deposition, sputtering and cleaning, all of which are performed on various substrates to form the desired device or product. Each of these processes may be performed using a single and distinct processing tool or module that performs a single fabrication process. Since multiple fabrication processes must be performed, substrates must be transferred from one processing tool to the next, which exposes the substrates to breakage and contamination. Further, transferring substrates between different processing tools increases the overall processing time and cost of fabrication.

[0005] A variety of process architectures are used in the industry. Traditional inline processing tools, which arrange processing tools linearly and move substrates sequentially from one processing tool to the next processing tool, are known to be inefficient, particularly when each processing tool requires different processing time as is commonly the case. For example, bottlenecks are common when substrates processed by a faster tool have to wait for their respective turn to be processed by a slower, downstream process tool.

[0006] Consequently, system architectures have been developed that provide multiple processing tools that can perform multiple fabrication processes. One commonly used example of a multiple processing tool is a cluster tool. The cluster tool employs multiple process chamber units arranged in a circular fashion typically connected to a single, large immobilized vacuum transfer chamber with one vacuum transfer robot to transfer substrates between the process chambers via multiple load lock chambers. Since substrates are transferred within a single tool for different fabrication processes, the potential for contamination is reduced. In addition, the substrates can be more quickly transferred between process chamber units, which reduces the overall processing time.

[0007] Traditional cluster tools however suffer several significant limitations. First there is a practical limit in the number of fabrication tools that may form the cluster. In order to add fabrication tools to the cluster, the transfer chamber size needs to increase to provide sufficient area to transport substrates from the transfer chamber to process chambers. This requires a long-reach transfer robot. Furthermore, adding a new tool to the cluster may require a whole new cluster tool if the capacity of the existing cluster tool is not sufficient to accommodate the new tool. Thus, the system is not easily expanded.

[0008] Second, the large immobile vacuum transfer chamber is of complex mechanical design and is not easily adapted to accommodate large substrates. For example, large glass or silicon substrates for photovoltaic or flat panel applications require a large rotating radius to turn the correspondingly large vacuum transfer chamber, and requires a large vacuum pump and expensive robot components that are rigid enough to perform such long stroke of travel.

[0009] Additionally, certain photovoltaic and semiconductor products involve processing steps of varied duration, causing significant bottlenecks in the processing line. For example, photovoltaic cells require deposition of multiple thin film layers of various thickness. Deposition of an intrinsic layer (“I-layer”), negative or n-doped layer (“N-layer”), and positive or p-doped layer (“P-layer”) often require significantly different deposition time to achieve the desired thickness. When deposition of a layer requiring short deposition time is followed by deposition of a layer requiring a long deposition time, the second layer creates a bottleneck and limits the throughput especially in a sequential or inline manufacturing process. The fabrication of multi junction photovoltaic cells further magnifies the problem.

[0010] Accordingly, further improvements are needed.

[0011] In general, embodiments disclosed herein relate to systems and methods for processing of substrates, such as but not limited to glass and other substrates used in the solar or photovoltaic industry, and wafers used in the semiconductor industry. More particularly, some embodiments disclosed herein relate to systems and methods for substrate processing comprising one or more mobile transverse chambers for transporting substrates between process modules.

[0012] In some embodiments a system for processing substrates is provided, comprising: one or more mobile transverse chambers configured to move between two or more process modules and to convey one or more substrates to at least one of two or more process modules. Each mobile transverse chamber is configured to independently maintain a specified gas condition during movement between process modules and during conveyance of the one or more substrates to the process modules.

[0013] In another embodiment, a system for processing substrates is provided, comprising: two or more process modules, each process module comprising a process chamber for processing the substrates; a substrate handling robot; a load lock chamber configured to receive the substrates from the substrate handling robot; and a transverse substrate handler configured to receive the substrates from the load lock chamber and transfer the substrates to at least one of the two or more process modules. The transverse substrate handler typically includes one or more mobile transverse chambers configured to move between the two or more process modules and to convey one or more substrates to at least one of the two or more process modules. Of particular advantage each mobile transverse chamber is configured to maintain a specified gas condition during movement between the process modules and during conveyance of the one or more substrates.

[0014] The system may be configured as a single line or in-line system, meaning that the transverse substrate handler and process modules are placed in a linear line fashion and the mobile transverse chamber(s) move linearly along the rail. Additionally, two parallel or dual in-line systems may be provided and optionally each line may be of different length. Further, the mobile transverse chamber(s) may service process modules positioned adjacent opposite sides of the mobile transverse chamber. Unlike inline systems of the prior art, the present invention provides flexibility, reduces bottlenecks and increases throughput, as described in more detail below. Many other types of arrangements are possible. For example and without limitation, the system may alternatively be configured as a cluster-type system, where the process modules and transverse substrate handler are positioned in a circular, U-shaped or other type of arrangement. Even further, the system may employ stacked process modules and an associated stacked transverse substrate handler. Thus, while certain specific embodiments are shown and described herein, those of skill in the art will recognize that various other system layouts and arrangement are possible and fall with the spirit and scope of the present invention.

[0015] In accordance with some embodiments described below, a system for processing substrates includes two or more process modules, a substrate handling robot, a load lock chamber, and a transverse substrate handler configured to receive the substrates from the load lock chamber and transfer the substrates to at least one of the two or more process modules. Each process module includes a process chamber for processing the substrates. The load lock chamber is configured to receive the substrates from the substrate handling robot. The transverse substrate handler includes one or more mobile transverse chambers configured to convey one or more substrates to at least one of the two or more process modules. Each mobile transverse chamber is configured to independently maintain a specified gas condition during the conveyance of the one or more substrates. The transverse substrate handler further includes one or more rails for supporting the one or more mobile transverse chambers, wherein the rail is positioned adjacent to entry of the process modules. One or more drive systems are provided for carrying and moving the one or more mobile transverse chambers on the rail.

[0016] A method for transferring substrates to two or more process modules is also provided and comprises conveying one or more mobile transverse chambers carried on a rail and positioned adjacent to the two or more process modules, and where each mobile transverse chamber is configured to independently maintain a specified gas condition during movement and conveyance of the substrates. The method also includes loading substrates into at least one of the one or more mobile transverse chambers, and actuating one or more drive systems to propel at least one of the one or more mobile transverse chambers along the rail. In addition, the method includes conveying at least one of the substrates from the mobile transverse chambers to at least one of the two or more process modules while maintaining the specified gas condition.

[0017] In another aspect, a method of transferring a substrate between two or more process modules or load lock station is provided, comprising: loading at least one substrate into one or more mobile transverse chambers, the mobile transverse chambers being carried on a rail positioned adjacent to the two or more process modules, and wherein each mobile transverse chamber is configured to maintain a specified gas condition during conveyance of the substrate; actuating one or more drive systems to propel the one or more mobile transverse chambers along the rail; docking the mobile transverse chamber to at least one of the process modules; and conveying the at least one substrate from the mobile transverse chamber to the at least one process modules.

[0018] In a further aspect, embodiments of the present invention provide for flexible transport of substrates while minimizing heat loss. For example, in one illustrative embodiment, a method of transferring one or more substrates between process modules or load lock stations is provided; comprising the step of: identifying a destination location D1 for a substrate S1 present at an initial processing location P1. If the destination location D1 is occupied with a substrate S2, the substrate S1 is maintained at the initial processing location P1. If the destination location D1 is available, the substrate S1 is transferred to the destination location D1. Additionally, if the destination D1 is occupied with the substrate S2 the method further comprises the step of identifying a destination location D2 for the substrate S2. In some embodiments, the method further comprises deciding which of the substrates S1 or S2 to transfer first to its respective destination location D1 or D2, based upon which of the substrates S1 or S2 has the longest processing time.

[0019] In yet a further aspect, a process module facility is provided comprising; at least one process chamber carried in frame, a subfloor adjacent the process module, at least one of a stationary pump and electrical box positioned atop the subfloor and gas control lines and vacuum exhaust lines housed within the subfloor and coupled to the process chamber.

[0020] In accordance with some embodiments, a method for transferring a substrate includes loading one or more substrates into a respective mobile chamber of one or more mobile chambers. The mobile chambers are movable on one or more rails positioned adjacent to two or more process modules. Each mobile chamber is configured to maintain a specified gas condition. The method also includes moving the respective mobile chamber along the one or more rails. The method further includes docking the respective mobile chamber to a respective process module of the two or more process modules, and conveying at least one of the one or more substrates from the respective mobile chamber to the respective process module. In some embodiments, the method also includes moving the respective mobile chamber along a second rail toward, or away from, the respective process module. The second rail is distinct from the one or more rails.

[0021] In accordance with some embodiments, a system for processing substrates includes one or more rails positioned adjacent to two or more process modules, and one or more mobile chambers. A respective mobile chamber of the one or more mobile chambers is configured to load one or more substrates, and maintain a specified gas condition. The respective mobile chamber is also configured to move on the one or more rails. The respective mobile chamber is further configured to dock with a respective process module of the two or more process modules, and convey at least one substrate of the one or more substrates to the respective process module. In some embodiments, the system includes a second rail, and the respective mobile chamber is configured to move along the second rail toward, or away from, the respective process module. The second rail is distinct from the one or more rails.

Brief Overview

[0044] In general, the embodiments disclosed herein relate to systems and methods for processing of substrates, such as but not limited to glass and other substrates used in the solar or photovoltaic industry, and wafers used in the semiconductor industry. More particularly, some embodiments disclosed herein relate to systems and methods for substrate processing comprising one or more mobile transverse chambers for transporting substrates between process modules and other stations such as a load lock.

[0045] In some embodiments a system for processing substrates is provided, comprising: one or more mobile transverse chambers configured to move between two or more process modules and to convey one or more substrates to at least one of two or more process modules. Each mobile transverse chamber is configured to independently maintain a specified gas condition during movement between process modules and during conveyance of the one or more substrates to the process modules.

[0046] Methods for transferring substrates to two or more process modules is also provided and comprises conveying one or more mobile transverse chambers carried on a rail and positioned adjacent to the two or more process modules, and where each mobile transverse chamber is configured to independently maintain a specified gas condition during movement and conveyance of the substrates. The method also includes loading substrates into at least one of the one or more mobile transverse chambers, and actuating one or more drive systems to propel at least one of the one or more mobile transverse chambers along the rail. In addition, the method includes conveying at least one of the substrates from the at least one of the one or more mobile transverse chambers to at least one of the two or more process modules while maintaining the specified gas condition.

[0047] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these particular details. In other instances, methods, procedures, components, and networks that are well-known to those of ordinary skill in the art are not described in detail to avoid obscuring aspects of the present invention.

[0048] It will also be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first contact could be termed a second contact, and, similarly, a second contact could be termed a first contact, without departing from the scope of the present invention. The first contact and the second contact are both contacts, but they are not the same contact.

[0049] The terminology used in the description of the embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the description of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0050] As used herein, the term “rail” may be construed to mean one or more rails. For example, a rail can be implemented as a set of two or more parallel rails.

[0051] Referring to FIGS. 1A, 1B, and 1C, there is shown one embodiment of a system of the present invention. The system 100 generally includes transverse substrate handler 110, load lock chamber 120, and two or more process modules 150, 152. Each process module 150, 152 comprises a process chamber for processing the substrates.

[0052] Any number of substrates and wafers may be processed using the system 100 and method of the present invention. For example, photovoltaic substrates, such as silicon, glass, or metal plates, and the like may be processed to form solar cells. Of particular advantage the flexibility of the system of the present invention enables use of multiple process recipes to form various devices and applications.

[0053] In some embodiments, PECVD modules may be respectively configured for depositing different layers of both doped and undoped layers used to create a photovoltaic device, for example P-doped, i.e. boron doped silicon layers, and I, i.e. intrinsic silicon layers and N-doped, i.e. phosphorous doped silicon layers. In some embodiments, each process module is configured to deposit one type of layer only, such as one type among the P, I, or N layers.

[0054] In one exemplary embodiment, a single junction photovoltaic or solar cell is fabricated using the system 100 of the present invention. More specifically, a glass substrate with a transparent conductive oxide (TCO) film, such as but not limited to ZnO, may be deposited. After laser scribing to divide the TCO layers, subsequent layers of p-doped silicon, intrinsic silicon and n-doped silicon layers are deposited in the system of the present invention. The resulting film is further separated into cells followed by a TCO back contact layer formed by deposition.

[0055] Of significant advantage the overall flexible system architecture of the present invention enables one to selectively configure the system layout as desired. To form a solar or photovoltaic cell, the system 100 of the present invention utilizes a greater number of process modules for deposition of I-layer silicon or N-layer silicon than the number of process modules for deposition of P-layer silicon. As shown in FIG. 1A, multiple I/N layer modules 152-1, 152-2, . . . 152-5 are employed in-line in the system. Because the deposition of N-layers and I-layers may take more time than the deposition of P-layers, providing more process modules in the system 100 for deposition of I-layer silicon or N-layer silicon than the number of process modules for deposition of P-layer silicon can expedite the substrate processing.

[0056] In another exemplary embodiment, a tandem or multiple junction solar cell is fabricated using the system 100 of the present invention by repeating P-I-N layer deposition in the same system. In another embodiment, multi junction solar cells are fabricated by deposition processes carried out on multi-line system configurations of the present invention.

System Architecture Embodiments

[0057] Referring to FIGS. 1A, 1B, and 1C, there is shown one embodiment of a system of the present invention illustrated in perspective, top and side views, respectively. The system 100 generally includes transverse substrate handler 110, load lock chamber 120, and two or more process modules 150, 152. Each process module 150, 152 comprises a process chamber for processing the substrates.

[0058] Substrates or wafers 115 are received from a main processing line or conveyors in a photovoltaic or semiconductor fab or foundry. A substrate handling robot (not shown) as well known in the art is generally configured to pick up substrates from the main processing line and to convey the substrates to particular stations for specific processing. In the exemplary embodiment the substrate handling robot is configured to transport the substrate to the load lock chamber 120. Typically the substrate handling robot includes an end effector (not shown) as is well known in the art. In some embodiments, the robot can transport multiple substrates simultaneously. For example, a dual-blade type robot system may be used to transport a substrate from the main processing line after picking up a processed substrate from the load lock chamber 120. The substrate handling robot may be configured to move horizontally to transport substrates to and from the load lock chamber 120 and then back to the main processing line. Alternatively, or optionally additionally, the substrate handling robot may be configured to move vertically to transport substrates between modules that are stacked or are positioned at different heights. For example, as shown in FIGS. 1A and 1C the system 100 optionally includes pre-heater 130 and a cooler (e.g., cool down rack 140), which are located near the load lock chamber 120. In some embodiments, the pre-heater 130 is configured to pre-heat substrates prior to loading the substrates into the load lock chamber 120. In some embodiments, the pre-heater 130 is configured to pre-heat one or more substrates prior to loading the substrates into a mobile transverse chamber 112 (also called herein a mobile chamber). In some embodiments, the system 100 includes a plurality of pre-heaters 130. In some embodiments, the cool down rack 140 is configured to cool a substrate after depositing a layer of material on a surface of the substrate. In some embodiments, the cool down rack 140 is configured to cool a plurality of substrates. Alternatively or additionally, a process module 150 or 152, or a mobile transverse chamber 112 cools the substrate. In some embodiments, the cooler is an active cooler, which cools the substrate using one or more refrigeration elements, such as coolants or thermoelectric elements. In other embodiments, the cooler is a passive cooler. In some embodiments, the system 100 includes a plurality of cool down racks 140. The substrate handling robot may move vertically to transport substrates between the processing line and the pre-heater 130 and/or the cool down rack 140 and/or the load lock chamber 120 depending upon the desired sequence of processing. In another embodiment, a rotating robot is positioned adjacent to the conveyor, and between the preheater 130 and cool down rack 140 on one side of the robot and the load lock chamber 120 on another side of the robot, such that the robot services both the load lock 120 and the preheater/cool down rack.

[0059] Load lock chamber 120 may include two entrance slits 122, 124. The first entrance slit 122 is configured to receive a substrate from the substrate handling robot, and to permit removal of the processed substrate from system 100 and back to the main processing line. The second entrance slit 124 is configured to convey a substrate to and from the transverse substrate handler 110. Typically, the load lock chamber 120 is configured to maintain a desired gas condition and creates an isolated environment for the substrate or wafer. In some examples, the desired gas condition is a reduced pressure, or vacuum environment.

[0060] The transverse substrate handler 110 is generally configured to receive the substrates from load lock chamber 120 and to transfer the substrates to at least one of the two or more process modules 150, 152. The transverse substrate handler 110 generally comprises one or more mobile transverse chambers 112, rail 114, and one or more drive systems 116.

[0061] Each mobile transverse chamber 112 is configured to convey one or more substrates to at least one of the two or more process modules 150, 152. The mobile transverse chamber 112 is carried by rail 114 (e.g., two parallel rails as illustrated in FIG. 1A), and is propelled along rail 114 by one or more drive systems 116. In some embodiments, the mobile transverse chamber 112 is configured to convey a single substrate. In some other embodiments, the mobile transverse chamber 112 is configured to convey two substrates, where the first substrate is conveyed for processing in one of the processing modules 150, 152, and the second substrate is processed by one of the processing modules 150, 152. In yet other embodiments, the mobile transverse chamber 112 is configured to convey the substrates in pairs.

[0062] Of particular advantage, the transverse substrate handler 110 comprises two or more mobile transverse chambers where each mobile transverse chamber 112 is configured to independently maintain a desired gas condition as the mobile transverse chamber moves between process modules. In other words, each mobile transverse chamber is configured to maintain a gas condition specified by the user during the conveyance of the substrates, and the gas condition may differ for each mobile transverse chamber. This enables significant flexibility in processing of the substrates. For example, to accommodate more than one mobile transverse chamber, a handoff station (not shown) is provided configured to receive substrates from one mobile transverse chamber and to convey to another mobile transverse chamber while maintaining the desired gas condition.

[0063] In some embodiments, the transverse substrate handler 110 may include two mobile transverse chambers 112. Each mobile transverse chamber is configured to independently maintain a specified gas condition during conveyance of the substrates. In some embodiments, the gas condition is the pressure inside the mobile transverse chamber. In other embodiments the gas condition is the type of gas environment in the mobile transverse chamber, and for example may include air; inert gas such as Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), and Xenon (Xe). Since the mobile transverse chamber contains an isolated environment it is even possible to configure the chamber to maintain a desired chemical environment, for example to select reactive gas(es) as the gas condition, such as silane (SiH₄), oxygen (O₂), dichlorosilane (SiCl₂H₂), nitrous oxide (N₂O), tetraethylorthosilicate (TEOS; Si(OC₂H₅)₄), phosphine (PH₃), arsine (AsH₃), diborane (B₂H₆), and the like, and mixtures thereof. The pressure of gas can range from vacuum to atmospheric pressure.

[0064] In another aspect of the present invention, the mobile transverse chamber 112 is configured to additionally maintain a desired thermal environment as well as the desired gas condition. In this example, the mobile transverse chamber may be heated. In this embodiment the mobile transverse chamber further includes a heat source. For example, without limitation, the mobile transverse chamber may be configured to promote oxidation or growth of a native oxide by heating the interior of the mobile transverse chamber while maintaining an oxygen rich environment inside the chamber.

[0065] In one illustrative embodiment, gas is maintained in the mobile transverse chamber at a pressure in the range of about 500 to 1000 mTorr, more usually in the range of 50 to 100 mTorr. In other words, in some embodiments, the mobile transverse chamber is configured to maintain a pressure in the range of about 50 mTorr to 1 Torr. In some embodiments, the mobile transverse chamber maintains a gas condition such that the difference between the pressure in the mobile transverse chamber and the process module (ΔP) is in the range of about 10 to 50 mTorr. In some embodiments, the mobile transverse chamber maintains a gas condition such that the difference between the pressure in the mobile transverse chamber and the process module (ΔP) is in the range of about 10 to 500 mTorr.

[0066] Rail 114 supports the one or more mobile transverse chambers 112. The rail 114 is positioned adjacent to entry of the process modules 150, 152. In some embodiments, the rail 114 supports the weight of the mobile transverse chambers 112. In some embodiments, the rail 114 supports the movement of the mobile transverse chambers 112. In other words, in some embodiments, the mobile transverse chambers 112 are movable on the rail 114. For example, the rail may be a support rail, which contacts the mobile transverse chambers through one or more mechanical bearings, to support the weight of the mobile transverse chambers 112. In another example, the rail 114 may be a drive rail, which is used to propel the mobile transverse chambers 112. In yet another example, the rail 114 may further include a guide or guide rail which guides the movement of the mobile transverse chambers 112 to prevent rotating or tilting of the transverse module. Leveling mechanisms may also be carried on the rail. A single rail 114 may provide multiple functions described above. In some embodiments, the system 100 includes two or more rails 114 as illustrated in FIG. 1A. In some embodiments, the system 100 includes one mobile transverse chamber 112 on each rail or each set of rails 114. In some embodiments, the system 100 includes two or more mobile transverse chambers 112 on each rail or each set of rails. In some embodiments, a single rail comprises two parallel support rails to spread the load of the transfer module and to provide anti-rotation of the module along the rail axes.

[0067] A respective drive system 116 propels the mobile transverse chamber 112. In some embodiments, the drive systems 116 require additional components, such as a drive rail discussed above, to move the mobile transverse chambers 112. For example, the drive system 116 may include a linear motor, a rack and pinion system, or a pulley and belt system. In some embodiments, each mobile transverse chamber 112 has a respective drive system 116. In some embodiments, the drive systems 116 are attached to the rail 114. Alternatively, the drive system 116 may be independent of the rail. A cable track system may be used to provide pneumatic supply and electrical power to the transverse substrate handler.

[0068] Process modules 150, 152 may be comprised of any suitable process module used in the processing of semiconductor and PV devices. For example, suitable process modules include without limitation: chemical vapor deposition chambers (CVD), plasma enhanced chemical vapor deposition (PECVD) chambers, atomic layer deposition (ALD) chambers, etching chambers; physical vapor deposition (PVD) chambers, annealing furnace, rapid thermal annealing (RTP) furnace, atmospheric pressure CVD chamber (APCVD), evaporative coating chamber, and the like.

[0069] Many other embodiments of the present invention are possible. For example, referring to FIGS. 2 to 4, alternative embodiments are illustrated. More specifically, in FIG. 2 two parallel systems are shown where the mobile transverse chamber 112 services process modules 150, 152 positioned adjacent opposite sides of the mobile transverse chamber 112. In this embodiment one mobile transverse chamber 112 is carried on rail 114 and positioned between and a plurality of process modules. Here, transverse chamber 112 includes two openings or slits 154 and 155 on opposite sides of the transverse chamber 112.

[0070] Referring to FIG. 3, a U-shaped cluster type system is shown. In this embodiment the process modules and transverse substrate handler are positioned in a U-shaped arrangement with multiple sections of rail 114a, 114b and 114c. Alternatively, the system can be configured in a circular arrangement where the process modules and rail are arranged in a circle as shown in FIG. 4.

[0071] To increase throughput, or to decrease processing time, some embodiments of the system of the present invention employ stacked process modules with associated stacked transverse substrate handlers as illustrated in FIG. 5.

[0072] In the exemplary embodiments shown above, the substrates are transported and processed in a horizontal manner. In an alternative embodiment substrates may be transported vertically, and typically, but not necessarily, in pairs, as shown in FIGS. 6A and 6B. In this instance, the process modules are configured to support the substrates vertically during processing, and the mobile transverse chamber is configured to transport the one or more substrates in a vertical position.

[0073] Thus, while certain specific embodiments are shown and described herein, those of skill in the art will recognize that various other system layouts and arrangement are possible and fall within the spirit and scope of the present invention. As shown, the flexibility of the inventive system enables multiple system configurations and layouts.

Transverse Substrate Handler and Mobile Transverse Chamber

[0074] The system of the present invention provides significant flexibility with respect to processing of substrates, particularly in connection with large substrates that are otherwise cumbersome and difficult to process. Additionally, the flexibility of the present invention enables complicated process recipes to be carried out all in one integrated system. For example and without limitation, the present invention enables parallel processing of substrates which is particularly advantageous for substrates requiring both long processing time and short processing time. Of significant advantage, the mobile transverse chamber of the present invention is configured to move between two or more process modules and to convey one or more substrates to at least one of two or more process modules while maintaining a desired gas environment. Each mobile transverse chamber is configured to independently maintain a specified gas condition during movement between process modules and during conveyance of the one or more substrates to the process modules. Referring to FIGS. 7 and 8 isolated top plan and isometric views, respectively, are shown for one embodiment of a mobile transverse chamber 112. In FIG. 7 the mobile transverse chamber 112 is shown in a docking position at a load lock chamber or station 120. Mobile transverse chamber 112 is carried by rail 114, and in this example the drive system 116 is comprised of a linear motor assembly 160 which propels the mobile transverse chamber 112 in a linear fashion along the rail 114.

[0075] To transfer substrates to and from the mobile transverse chamber 112 and to and from a particular process module or other station, the mobile transverse chamber 112 further comprises a transfer robot assembly 170.

[0076] In general, transfer robot assembly 170 is configured to secure the substrate in the transverse chamber 112 during transport in a retracted position as depicted in FIG. 10, and to move the substrate to and from the process modules and other stations during processing in an extended position as depicted in FIG. 11.

[0077] In some embodiments, the transfer robot assembly 170 comprises a substrate holder 172 and a linear actuator. In some embodiments, the substrate holder 172 is configured to hold two or more substrates. For example, the substrate holder may have multiple slots to hold the two or more substrates. In another example, the substrate holder may be configured to hold two or more cartridges, where each cartridge is configured to hold one or more substrates. A linear actuator moves the substrate holder to allow a substrate or a cartridge to be loaded to an empty slot on the substrate holder, or to allow a substrate or a cartridge to be unloaded from a loaded slot on the substrate holder. The linear actuator may be comprised of any suitable actuator mechanism, such as for example without limitation: a rail and a linear motor; a rack and pinion system; or a pulley and belt system.

[0078] In an illustrative embodiment shown in FIGS. 9 to 11, the transfer robot assembly 170 is comprised of substrate holder 172 actuated by a swing arm mechanism 174. Substrate holder 172 can be formed of any suitable support. In one example substrate holder 172 is comprised of a solid flat plate. In another example, as shown in the figures, substrate holder 172 is comprised of multiple prongs 176 which support the substrate 115. In this embodiment, the substrate holder may further include holder rails 178 at the outer edges of the prongs 176. Holder rails 178 (also called rails) are configured to support the substrate at its edge and may also include a centering mechanism, such as stops or bumpers 179 to assist with centering and securing the substrate during transport.

[0079] Substrate holder 172 may be configured to support one or more substrates. In one embodiment, mobile transverse chamber 112 houses two substrates as shown in the cut-away view of FIG. 9. In this instance, a top substrate holder 172a and bottom substrate holder 172b are provided. Preferably, each substrate holder is independently configured to maximize flexibility of the system and to increase throughput.

[0080] Swing arm mechanism 174 is configured to actuate the substrate holder 172 and to move between a refracted and extended position as shown in FIGS. 10 and 11. As shown in FIG. 12 swing arm mechanism 174 is generally comprised of swing arm 180 and slide 182. One end of swing arm 180 moves within channel 183 of slide 182. The opposite end of swing arm 180 pivots about fixed post 184 via linkage and slider bearing 186 driven by swing arm drive shaft 188.

[0081] In some embodiments, the mobile transverse chamber 112 comprises two or more entrance slits. Referring again to FIG. 2, the first entrance slit 154 is located on one side of the mobile transverse chamber and the second entrance slit 155 is located on the opposite side of the mobile transverse chamber. In some embodiments, the entrance slits are used to convey substrates from one side of the mobile transverse chamber 112 to the other side of the mobile transverse chamber 112. For example, the process modules 150, 152 may be located in two lines, and a rail may be positioned between the two lines. The mobile transverse chamber 112 may load or unload substrates from the process modules positioned on one side of the rail through the first entrance slit, and from the process modules positioned on the other side of the rail through the second entrance slit.

[0082] Of particular advantage the mobile transverse chamber 112 is configured to maintain a specified gas condition when transporting substrates within the system, and optionally when coupled to the process chambers and/or other stations. In some embodiments, the mobile transverse chamber 112 includes docking assembly 190 as illustrated in FIG. 8 and FIG. 13. In some embodiments, docking assembly 190 is carried on the mobile transverse chamber 112. In other embodiments, docking assembly 190 may be carried on the process module, as well as on the load lock chamber.

[0083] Docking assembly 190 is generally configured to facilitate transfer of the substrates from the mobile transverse chamber to a process module or other station while maintaining the integrity of the environment in the mobile transverse chamber 112. Docking assembly 190 may further be configured to minimize cross contamination of the mobile transverse chamber by establishing a positive air or gas flow in the direction of the process module or other station. Thus, gas or air does not flow into the mobile transverse chamber when docking at a process chamber or other station. In one illustrative embodiment, gas is maintained in the mobile transverse chamber at a pressure in the range of about 500 to 1000 mTorr, more usually in the range of 50 to 100 mTorr. In some embodiments the mobile transverse chamber maintains a gas condition such that the difference between the pressure in the mobile transverse chamber and the process module (ΔP) is in the range of about 10 to 50 mTorr.

[0084] Referring to FIG. 13, docking assembly 190 is comprised of a vacuum flange 192 and expandable membrane or bellows 194 configured to maintain the gas condition when coupled to a process module or other station. The expandable membrane or bellows 194 is typically made of stainless steel, titanium, superalloy, or any other corrosion-resistant metal. Membrane 194 is typically deformable. The vacuum flange 192 may comprise a flange, an O-ring, and a lip seal, and is arranged to mate with a flat seal surface on the process chamber or load lock by pneumatically actuated cylinder clamps 195.

[0085] Coupled to the expandable or deformable membrane 194 is a vacuum source attached to the stationary side of buffer media pumping port 198. A buffer media vent valve 199 may also be provided. In one example a stationary pump 200 is installed near the load lock and lines are connected to the buffer media pump ports 198 at each process chamber. When the mobile transverse chamber is docked at a process module, an air pocket or gap is formed between the expandable bellows 194 and the process module. Stationary pump 200 is coupled to buffer media pumping port 198 and is configured to pump down this air gap to vacuum prior to opening of the process chamber and transfer of the substrate from the mobile transverse chamber. This creates positive air flow in the direction of the process chamber and thus isolates the mobile transverse chamber 112 from any reactant gases or other contaminants present in the process chamber.

[0086] Alternatively, at least one process module includes a stationary pump 200 configured to evacuate air in the air gap between the mobile transverse chamber 112 and a process module 150, 152 or a load lock chamber 120 when the mobile transverse chamber 112 is coupled to a respective process module 150, 152 or a load lock chamber 120.

[0087] In yet a further embodiment, a mobile evacuation pump 196 carried on the mobile transverse chamber 112, and the stationary pump 200 carried on the process module or load lock are provided. In this embodiment, the mobile evacuation pump 196 may be employed to evacuate the air gap formed between the mobile transverse chamber and the process chamber when docked. Once the air gap is evacuated, the process chamber opens and then the stationary pump 200 evacuates both the process chamber and the mobile transverse chamber. This provides significant flexibility and advantage since the stationary pump 200 may be configured to be of a sufficiently large capacity to evacuate a relatively large cavity, whereas the evacuation pump 196 may be of smaller capacity for evacuating only the air gap and thus easily carried on a mobile platform. Alternatively, the stationary pump 200 is used to evacuate the air gap and to further evacuate the mobile transverse chamber and process chamber or load lock during transfer of the substrates.

[0088] In some embodiments, the mobile evacuation pump 196 is further configured to evacuate the mobile transverse chamber 112 to maintain a gas condition while the mobile transverse chamber 112 is being moved. For example, a pressure inside the mobile transverse chamber 112 is monitored, and when the pressure exceeds a predefined threshold, the mobile evacuation pump 196 is operated until the pressure reaches a predefined target pressure.

[0089] In another embodiment, a large pump may be used in conjunction with a series of vacuum lines connected to each of the buffer media ports 198 and isolated by air operated valves at the port 198. In this embodiment, the vacuum lines may act as a vacuum reservoir enabling fast evacuation of the air gap.

[0090] To assist with docking, a number of leveling and/or guide mechanisms may be employed. For example, as shown in FIG. 13, leveling mechanisms 210 are included on the frame assembly and/or mobile transverse chamber 112. Any suitable leveling mechanism may be used, such as for example, without limitation: adjustment rods, compression tie rods, leveling hitch ball, and the like. A balance track 212 may also be incorporated into the frame for additional stability. Safety guide rollers 214 may further be incorporated into the rail 114 and/or carried on the bottom of the mobile transverse chamber 112. The cable carrier track 115 houses the electrical and air lines, and may be comprised of a flexible belt or track like linkage.

[0091] FIGS. 14A and 14B depict partial, cut-away side views of a mobile chamber 112 in accordance with some embodiments. In some embodiments, the mobile chamber 112 has a docking mechanism that includes a docking plate 1410 and a membrane 194. The docking plate 1410 is coupled with one or more cylinders 197, which are typically pneumatically actuated. The docking plate 1410 is coupled with an O-ring and/or a lip seal 1420. In some embodiments, the membrane 194 is coupled with the mobile chamber 112 around an opening of the mobile chamber 112. The membrane 194 is also coupled with the docking plate 1410. When the mobile chamber 112 is docked with a process module 152 (FIG. 14B), the one or more cylinders 197 move the docking plate 1410 toward the process module 152 such that the O-ring 1420 is pressed on a front surface of the process module 152 to create a seal. Typically, the docking plate 1410 is coupled with a plurality of cylinders 197, which are located around a perimeter of the docking plate.

Methods of Substrate Handling and Docking

[0092] Of particular advantage, the present invention promotes flexible substrate processing. FIG. 15 illustrates a method for transferring substrates to two or more process modules in accordance with some embodiments. At step 1010, one or more mobile transverse chambers are provided. The mobile transverse chambers are carried on a rail 114, and are movable along the rail. The rail is positioned adjacent to two or more process modules so that the mobile transverse chambers can couple or dock with a respective process module.

[0093] Each mobile transverse chamber is configured to independently maintain a specified gas condition during conveyance of the substrates and/or when they contain one or more substrates. In some embodiments, the gas condition includes the pressure inside the mobile transverse chamber. In some embodiments, the gas condition includes the type of gas environment in the mobile transverse chamber, and for example may include air, or inert gas, such as Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), and Xenon (Xe). In yet further embodiments, the gas condition may be comprised of reactive gas(es) such as silane (SiH₄), oxygen (O₂), dichlorosilane (SiCl₂H₂), nitrous oxide (N₂O), tetraethylorthosilicate (TEOS; Si(OC₂H₅)₄), phosphine (PH₃), arsine (AsH₃), diborane (B₂H₆), and the like, and mixtures thereof. Thus, in some embodiments, the gas condition includes the vacuum pressure inside the mobile transverse chamber. In some embodiments, the gas condition includes the pressure of one or more types of gas inside the mobile transverse chamber.

[0094] The pressure inside the mobile transverse chamber may range from vacuum to atmospheric pressure. In one illustrative embodiment, gas is maintained in the mobile transverse chamber at a pressure in the range of about 500 to 1000 mTorr, more usually in the range of 50 to 100 mTorr. In some embodiments, the mobile transverse chamber maintains a gas condition such that the difference between the pressure in the mobile transverse chamber and the process module (ΔP) is in the range of about 10 to 50 mTorr. The mobile transverse chambers maintain independently controlled environments, and thus when two mobile transverse chambers are provided, the first mobile transverse chamber may convey substrates at one gas condition such as under vacuum, and the second mobile transverse chamber may convey substrates in a second gas condition such as in an argon atmosphere.

[0095] At step 1020, substrates are loaded into at least one of the one or more mobile transverse chambers. In some embodiments, loading substrates into at least one of the mobile transverse chambers can be performed by operating the transport robot assembly 170. In some embodiments, prior to operating the transport robot assembly 170, a flange is used to couple the mobile transverse chamber to a load lock chamber 120 or a processing module 150, 152. In some embodiments, an evacuation pump is used to evacuate the air pocket between the mobile transverse chamber and the load lock chamber or the processing module.

[0096] At step 1030, one or more drive systems are actuated to propel at least one of the one or more mobile transverse chambers along rail 114. The drive system may include a linear motor, a rack and pinion system, or a pulley and belt system. The drive system is operated to move the mobile transverse chambers along rail 114 and position the mobile transverse chambers adjacent to a load lock chamber or a respective processing module. In some embodiments, the drive system includes position sensors or contact sensors to determine the position of the mobile transverse chamber. In some embodiments, the drive system includes a feedback control mechanism to improve the motion and positioning of the mobile transverse chambers.

[0097] At step 1040, at least one of the substrates are conveyed from at least one mobile transverse chamber to at least one of the two or more process modules. In some embodiments, substrates are conveyed from the mobile transverse chamber to the process module by operating the transport robot assembly 170. Similar to the loading process at step 1020, a flange may be used to couple the mobile transverse chamber to a processing module 150, 152. In some embodiments, an evacuation pump is used to evacuate the air pocket between the mobile transverse chamber and the load lock chamber or the processing module.

Method of Substrate Transport while Minimizing Heat Loss

[0098] In another aspect, a method of transferring a substrate while minimizing heat loss is provided as illustrated generally in the flowchart of FIG. 16a. In some embodiments, a scheduler 1200 is employed to establish operational flow control rules for the transport of one or more substrates.

[0099] In some embodiments, scheduler 1200 is configured as a state machine. In this example, the primary function of scheduler 1200 is to coordinate the various components of the system 100, thus providing comprehensive operational flow of the substrates throughout processing.

[0100] The scheduler 1200 is typically configured to maximize throughput performance of the system 100. In some embodiments, the scheduler 1200 is advantageously configured to promote process consistency, meaning in this context maintaining substantial temperature constancy, or minimizing heat loss, of the substrates while transferring the substrates between processing modules via the mobile transverse chambers. The scheduler 1200 is generally configured to employ forward looking scheduling methods to minimize the amount of time any one substrate is housed in a mobile transverse chamber.

[0101] In one embodiment, scheduler 1200 is configured according to the following forward looking rules:

[0102] (a) whenever a substrate has completed processing in one of the process chambers, the scheduler will not initiate transfer of the substrate from the process chamber until it can establish or reconcile a transfer path for the substrate within the system 100. This means that no substrate will reside idle in a mobile transverse chamber waiting for the availability of the next processing or transfer station, such as for example the load lock chamber, process module, or any other processing station. Thus, the scheduler is configured such that the scheduler does not initiate a substrate transfer or transport action unless and until there is an open path such that the substrate can be delivered to its next processing or transfer point; and

[0103] (b) a substrate residing in a process module with the longest processing time has highest priority with respect to substrate transport.

[0104] In one example, the above rules may be implemented as illustrated in the flowchart of FIG. 16a, which shows one embodiment of transport path reconciliation logic for a processed substrate. At step 1210, the method is initiated upon completion of processing of a particular substrate S1 housed in process chamber P1. At step 1220, an inquiry is made regarding the job flow status for substrate S1. Specifically, the next destination location or chamber for substrate S1 is identified. At step 1230, the inquiry is made regarding whether the next destination location or chamber D1 for substrate S1 is available. If no, the substrate S1 remains in process chamber P1 at step 1240. If yes, the inquiry is made regarding whether another substrate S2 is currently located in the destination location or chamber D1 at step 1250. If no, then the scheduler initiates the transport of substrate S from process chamber P1 to destination location or chamber D1 at step 1260. If yes, then the scheduler inquires regarding the job flow status of substrate S2 and the identity of its destination location or chamber D2 at step 1220. While one particular implementation has been described herein, those of skill in the art will recognize that other implementations of the forward looking scheduler rules are possible within the scope and teaching of the system.

[0105] For example, in one illustrative embodiment, a method of transferring one or more substrates between process modules or load lock stations may be carried out as follows: a destination location D1 for a substrate S1 present at an initial processing location P1 is identified. If the destination location D1 is occupied with a substrate S2, the substrate S1 is maintained at the initial processing location P1. If the destination location D1 is available, the substrate S1 is transferred to the destination location D1. Additionally, if the destination D1 is occupied with the substrate S2, the method further comprises the step of identifying a destination location D2 for the substrate S2. In some embodiments, the method further comprises deciding which of the substrates S1 or S2 to transfer first to its respective destination location D1 or D2, based upon which of the substrates S1 or S2 has the longest processing time

[0106] FIG. 16b is a block diagram of computer system 1300 for controlling the system and implementing the method according to some embodiments of the present invention. The system 1300 generally includes one or more processing units (CPU's) 1302, optionally one or more network or other communications interfaces 1304, memory 1310, and one or more communication buses 1308 for interconnecting these components. The communication buses 1308 may include circuitry (sometimes called a chipset) that interconnects and controls communications between system components. The system 1300 may optionally include a user interface, for instance a display 1306 and an input device 1305. Memory 1310 may include high speed random access memory and may also include non-volatile memory, such as one or more magnetic disk storage devices. Memory 1310 may include mass storage that is remotely located from the central processing unit(s) 1302.

[0107] Memory 1310, or alternatively the non-volatile memory device(s) within memory 1310, comprise a computer readable storage medium. In some embodiments, memory 1310 stores the following programs, modules and data structures, or a subset thereof:

• • [0108] an operating system 1311 that includes procedures for handling various basic system services and for performing hardware dependent tasks;
  • [0109] an optional network communication module 1312 that is used for connecting the system 1300 to other computers via the one or more communication network interfaces 1304 (wired or wireless) and one or more communication networks, such as the Internet, other wide area networks, local area networks, metropolitan area networks, and so on;
  • [0110] transport operating modules 1320 that control or manage instructions to transport substrates between load lock station, process modules, and the like, via the mobile transverse chambers, and for loading and unloading of substrates from the mobile transverse chambers, load lock stations and process modules;
  • [0111] process chamber operating module 1330 that controls or manages instructions to control the processing steps and recipes for processing the substrates to form the p-i-n junctions and the like to form the photovoltaic cells; and
  • [0112] scheduler module 1340 that controls or manages instructions to control the hierarchy and path of flow of substrates throughout the system as shown in the flowchart of FIG. 16a.

[0113] Each of the above identified elements may be stored in one or more of the previously mentioned memory devices, and corresponds to a set of instructions for performing a function described above. The above identified modules or programs (i.e., sets of instructions) need not be implemented as separate software programs, procedures or modules, and thus various subsets of these modules may be combined or otherwise re-arranged in various embodiments. In some embodiments, memory 1310 may store a subset of the modules and data structures identified above. Furthermore, memory 1310 may store additional modules and data structures not described above.

[0114] Although FIG. 16b shows a “system,” FIG. 16b is intended more as functional description of the various features that may be present in a set of processors (e.g., in clients or in servers) than as a structural schematic of the embodiments described herein. In practice, and as recognized by those of ordinary skill in the art, items shown separately could be combined and some items could be separated. For example, some items shown separately in FIG. 16b could be implemented on single servers and single items could be implemented by one or more servers. The actual number of resources used to implement a system and how features are allocated among them will vary from one implementation to another.

[0115] The method may be governed by instructions that are stored in a computer readable storage medium and that are executed by one or more processors of one or more servers. Each of the operations shown in FIG. 16a and FIG. 16b may correspond to instructions stored in a computer memory or computer readable storage medium. The computer readable storage medium may include a magnetic or optical disk storage device, solid state storage devices such as Flash memory, or other non-volatile memory device or devices. The computer readable instructions stored on the computer readable storage medium are in source code, assembly language code, object code, or other instruction format that is interpreted by one or more processors.

Process Chamber Integrated Facility

[0116] In another aspect of the system, a process module facility 300 is provided having integrated facilities as illustrated in FIG. 17. In one embodiment, the process module facility generally comprises process chamber 302 carried in frame 304, subfloor 306, and process chamber pump 308. Subfloor 306 may house gas control lines and other piping (not shown). Process chamber pump 308 is preferably located adjacent to the process chamber 302 and is coupled to the process chamber 302 via gas control lines typically located in subfloor 306. Optionally, and additionally, electrical controls 310 may be housed adjacent to the process chamber and coupled to the process chamber via electrical wires (not shown) typically housed in the subfloor 306. This is of particular advantage with existing semiconductor fabs since the integrated facility 300 of the present invention is modular and flexible, and may be easily incorporated in existing fabs that generally sit on concrete slabs.

Multi-Rail Configuration

[0117] In some embodiments, a system includes a mobile chamber that is configured to move in multiple directions. For example, as illustrated in FIGS. 18A, 18B, 18C, and 18D, a mobile chamber 112 can move in two non-parallel directions (i.e., a first direction along the rail 114 and a second direction that is not parallel to the first direction; in some embodiments, the first direction is perpendicular to the second direction). In FIG. 18A, the mobile chamber 112 moves toward the load lock 112 for loading and/or unloading one or more substrates. After loading/unloading the one or more substrates, the mobile chamber 112 moves away from the load lock 112, as shown in FIG. 18B. In FIG. 18C, the mobile chamber 112 moves along the rail 112. In FIG. 18D, the mobile chamber 112 moves toward a process module 150, and docks with the process module 150. Thereafter, at least one substrate in the mobile chamber 112 is conveyed to the process module 150.

[0118] In some embodiments, the mobile chamber 112 moves toward or away from a load lock or a process module (e.g., the load lock 120 or the process module 150 in FIG. 18A) on a second rail. For example, FIGS. 19A, 19B, and 19C depict cross-sectional views of a system with two rails in accordance with some embodiments. The system depicted in FIGS. 19A, 19B, and 19C includes a first rail (e.g., rail 114), and a mobile base 113 that is configured to move along the first rail. The mobile base 113 is coupled with a second rail 118. Thus, the second rail 118 is movable on the first rail simultaneously with the mobile base 113. The second rail 118 is positioned along a direction non-parallel (e.g., typically perpendicular, but optionally at any other angle) to the first rail. A mobile chamber 112 is configured to move along the second rail, as illustrated in FIG. 19B. The position of the mobile chamber 112 as illustrated in FIG. 19A is called herein an “at-rest” position. In some embodiments, the mobile chamber 112 is configured to move in one of two opposite directions from the at-rest position. In other words, in some embodiments, the mobile chamber 112 is configured to move in a first direction from the at-rest position, as illustrated in FIG. 19B, and the mobile chamber 112 is also configured to move in a second opposite direction from the at-rest position, as illustrated in FIG. 19C.

[0119] In some embodiments, the mobile chamber 112 includes two entrance slits 154 and 155, as shown in FIGS. 19A, 19B, and 19C. When process modules are positioned on two opposite sides of the mobile chamber 112 as illustrated in FIG. 2, the mobile chamber 112 can move toward respective process modules to facilitate the conveyance of one or more substrates. For example, a first process module is positioned toward the first-entrance-slit side of the mobile chamber 112, and a second process module is positioned toward the second-entrance-slit side of the mobile chamber 112. The mobile chamber 112 moves in a first direction toward the first process module (e.g., FIG. 19B) along the second rail 118, and docks with the first process module. After the mobile chamber 112 docks with the first process module, one or more substrates are conveyed through the first entrance slit 154 (e.g., from the mobile chamber 112 to the first process module, or from the first process module to the mobile chamber 112). Thereafter, the mobile chamber 112 moves toward the second process module (e.g., FIG. 19C) along the second rail 118, and docks with the second process module. After the mobile chamber 112 docks with the second process module, one or more substrates are conveyed through the second entrance slit 155 (e.g., from the mobile chamber 112 to the second process module, or from the second process module to the mobile chamber 112).

[0120] In addition, the mobile chamber 112 can work with a process module on one side and a load lock on the opposite side, or with two load locks on two opposite sides, in manners similar to those described above with respect to FIGS. 19A, 19B, and 19C. For brevity, the details of such operations are omitted.

[0121] FIGS. 20A and 20B depict simplified top views of a system in operation in accordance with some embodiments. In some embodiments, the system with the first and second rails includes a linkage mechanism configured to securely move a respective mobile chamber 112 toward (and back from) a respective process module 152 for docking (and undocking) The linkage mechanism is also called herein a cam-over mechanism. The linkage mechanism includes a plurality of links 2020 (e.g., rods or bars). In some embodiments, the linkage mechanism includes an actuator 2010 configured to move the links 2020. In some embodiments, the actuator 2010 is a pneumatically-actuated air cylinder. The actuator 2010 is coupled at least with a first link of the links 2020. The first link is also coupled with a follower 2040, which is configured to slide along a linear slide 2030. In some embodiments, the linkage mechanism also includes a second link of the links 2020. The second link is coupled with the follower 2040. The second link is also coupled with the respective mobile chamber 112. For example, the second link may be rotatably attached to the respective mobile chamber 112 with a ball and socket joint. In some embodiments, the actuator 2010 is mounted on a mobile base 113 (FIG. 19A). In some embodiments, the linear slide 2030 is mounted on the mobile base 113, typically at a fixed location on the mobile base. As illustrated in FIGS. 20A and 20B, in some embodiments, the linkage mechanism includes a pair of first links and a pair of second links.

[0122] For a docking operation, the actuator 2010 pushes out the first link, sliding the follower 2040 along the linear slide 2030. The follower 2040, in turn, moves the second link, which pushes the respective mobile chamber 112 toward the respective process module 152 (toward a docking position). For an undocking operation, the actuator 2010 pulls the first link, causing the follower 2040 and the second link to move, and the respective mobile chamber 112 to move away from the respective process module 152 (toward a retracted position).

[0123] The link mechanism illustrated in FIGS. 20A and 20B has advantages over a direct drive mechanism that moves the respective mobile chamber 112 with the actuator 2010 without the link mechanism, especially when the actuator 2010 is pneumatically operated. With the direct drive mechanism, any loss or fluctuation of a pneumatic pressure (e.g., air pressure) to the actuator 2010 may cause the respective mobile chamber 112 to move away from the respective process module 152, resulting in a loss of the specified gas condition in the respective mobile chamber 112. The link mechanism illustrated in FIGS. 20A and 20B reduces the movement of the respective mobile chamber 112 away from the respective process module 152 during docking due to such a loss of the pneumatic pressure. Such movement of the respective mobile chamber 112 is also called a back drive. This benefit is achieved by reducing a force at the actuator 2010 required to maintain the respective mobile chamber 112 in the docking position. Stated differently, any force in a direction along the second rail 118 to move the respective mobile chamber 112 away from the respective process module 152 has little or no force in a direction along the linear slide 2030, and thus such force in the direction along the second rail 118 does not easily move the follower 2040 along the linear slide 2030, which is required to move the respective mobile chamber 112 away from the respective process module 152.

[0124] In some embodiments, the mobile chamber is coupled with a gear mechanism including an activatable gear lock (e.g., a latch or a pin). The gear mechanism is driven when the respective mobile chamber 112 moves along the second rail 118. Typically, the gear mechanism, if present, moves the respective mobile chamber 112 along the second rail 118. When the gear lock is engaged, the gear lock prevents driving the gear mechanism, and thus prevents the respective mobile chamber 112 from moving along the second rail 118. In some embodiments, the gear mechanism includes a worm gear. In some embodiments, the system includes one or more mobile chamber locks (e.g., a clamp or a tab). The one or more mobile chamber locks prevent the movement of the respective mobile chamber 112, and thus prevent the back drive.

[0125] In some embodiments, a system includes a plurality of fixed rails. As illustrated in FIG. 21, the system 100 includes a rail 114 and a plurality of second rails 117 (e.g., 117-1, 117-2, 117-3, and 117-4). A respective second rail is positioned adjacent to a respective process module (e.g., a second rail 117-1 is positioned adjacent to a process module 150, and a second rail 117-2 is positioned adjacent to a process module 152-3, etc.). Furthermore, a respective second rail is typically positioned in a direction that is non-parallel to a direction along the rail 114 (e.g., respective second rails 117 in FIG. 20 are perpendicular to the rail 114). In some embodiments, the mobile chamber 112 is configured to move to a respective process module along a respective second rail (e.g., the mobile chamber 112 can move toward the process module 150 along the second rail 117-1).

[0126] FIG. 22 depicts a cross-sectional view of a system with a plurality of rails (e.g., the system 100 illustrated in FIG. 21) in accordance with some embodiments. The system illustrated in FIG. 22 includes a rail 114 and a mobile base 113 that is configured to move along the first rail, as explained above with reference to FIG. 19A. The mobile chamber 112 is configured to move on the mobile base 113 toward a second rail 117 by using an actuator mechanism (e.g., wheels and a motor, a linear motor, or a rack and pinion system). The mobile chamber 112 is further configured to move along the second rail 117 toward or away from a respective process module (e.g., the process module 152-1) for conveying one or more substrates.

[0127] In some embodiments, a first process module and a second process module are positioned on different sides of the mobile chamber 112, as illustrated in FIG. 2. In some embodiments, the system includes a second rail adjacent to the first process module (i.e., on one side of the mobile chamber 112) and a third rail (not shown) adjacent to the second process module (i.e., on the different side of the mobile chamber 112). In some embodiments, the mobile chamber 112 is configured to move toward the first process module along the second rail 117, and also configured to move toward the second process module along the third rail, in manners similar to those described above with reference to FIG. 22. For brevity, the details of such operations are omitted.

[0128] The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings and in the spirit of the invention. The specific embodiments described herein were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.